Guide: Cosmos SDK Hard Forks for Security Vulnerabilities

app.go

// BeginBlocker runs the Tendermint ABCI BeginBlock logic. It executes state changes at the beginning
// of the new block for every registered module. If there is a registered fork at the current height,
// BeginBlocker will schedule the upgrade plan and perform the state migration (if any).
func (app *App) BeginBlocker(ctx sdk.Context, req abci.RequestBeginBlock) abci.ResponseBeginBlock {
	// Perform any scheduled forks before executing the modules logic
	app.ScheduleForkUpgrade(ctx)
	return app.mm.BeginBlock(ctx, req)
}

constants.go

const (
	// UpgradeName is the shared upgrade plan name for mainnet and testnet
	UpgradeName = "v7.0.0"
	// MainnetUpgradeHeight defines the Evmos mainnet block height on which the upgrade will take place
	MainnetUpgradeHeight = 2_476_000
	// UpgradeInfo defines the binaries that will be used for the upgrade
	UpgradeInfo = `'{"binaries":{"darwin/arm64":"https://github.com/evmos/evmos/releases/download/v7.0.0/evmos_7.0.0_Darwin_arm64.tar.gz","darwin/x86_64":"https://github.com/evmos/evmos/releases/download/v7.0.0/evmos_7.0.0_Darwin_x86_64.tar.gz","linux/arm64":"https://github.com/evmos/evmos/releases/download/v7.0.0/evmos_7.0.0_Linux_arm64.tar.gz","linux/x86_64":"https://github.com/evmos/evmos/releases/download/v7.0.0/evmos_7.0.0_Linux_x86_64.tar.gz","windows/x86_64":"https://github.com/evmos/evmos/releases/download/v7.0.0/evmos_7.0.0_Windows_x86_64.zip"}}'`
)

forks.go

// ScheduleForkUpgrade executes any necessary fork logic for based upon the current
// block height and chain ID (mainnet or testnet). It sets an upgrade plan once
// the chain reaches the pre-defined upgrade height.
//
// CONTRACT: for this logic to work properly it is required to:
//
// 	1) Release a non-breaking patch version so that the chain can set the scheduled upgrade plan at upgrade-height.
// 	2) Release the software defined in the upgrade-info
func (app *App) ScheduleForkUpgrade(ctx sdk.Context) {
	// NOTE: there are no testnet forks for the existing versions
	if !types.IsMainnet(ctx.ChainID()) {
		return
	}

	upgradePlan := upgradetypes.Plan{
		Height: ctx.BlockHeight(),
	}

	// handle mainnet forks with their corresponding upgrade name and info
	switch ctx.BlockHeight() {
	case v2.MainnetUpgradeHeight:
		upgradePlan.Name = v2.UpgradeName
		upgradePlan.Info = v2.UpgradeInfo
	case v4.MainnetUpgradeHeight:
		upgradePlan.Name = v4.UpgradeName
		upgradePlan.Info = v4.UpgradeInfo
	case v7.MainnetUpgradeHeight:
		upgradePlan.Name = v7.UpgradeName
		upgradePlan.Info = v7.UpgradeInfo
	default:
		// No-op
		return
	}

	// schedule the upgrade plan to the current block hight, effectively performing
	// a hard fork that uses the upgrade handler to manage the migration.
	if err := app.UpgradeKeeper.ScheduleUpgrade(ctx, upgradePlan); err != nil {
		panic(
			fmt.Errorf(
				"failed to schedule upgrade %s during BeginBlock at height %d: %w",
				upgradePlan.Name, ctx.BlockHeight(), err,
			),
		)
	}
}